The microporous molecular sieve material has regular pore structures and a large surface area, thus is widely used in the fields of adsorption, separation, chemical engineering, catalysis and the like. In recent years, some new structures of molecular sieve materials have been prepared continuously.
IM-5 molecular sieve is a new zeolite prepared using a bi-quaternary ammonium salt as the templet agent. The IM-5 molecular sieve has a pore-passage structure similar to that of ZSM-5, has a two dimensional 10MR crossing pore structure, and has relatively high thermal stability and hydrothermal stability. Thus the ZSM-5 has a broad prospect of application for catalysis in the petrochemical fields of paraffin cracking, isomerization of n-butylene, preparation of gasoline from Synthesis Gas and the like.
Journal of Molecular Catalysis A: Chemical, 2000, 162: 175-189 Discloses to obtain an IM-5 molecular sieve from crystallization for 10 days using 1,1-(pentamethylene) bis-(1-methylpyrrolidinium) bromide as the templet agent, under the condition of adding a promoter of sodium bromide and static hydrothermal conditions at a temperature of 175 degrees C.
Journal of Catalysis 215 (2003) 151-170 discloses to obtain an IM-5 molecular sieve from crystallization for 14 days using 1,1-(pentamethylene) bis-(1-methylpyrrolidinium) bromide as the templet agent, under the dynamic hydrothermal condition at a temperature of 160 degrees C.
CN1234012A discloses an IM-5 molecular sieve and the preparation process thereof. The IM-5 molecular sieve is obtained with high crystallinity from hydrothermal crystallization for 8 days at a temperature of 170 degrees C. by adding additional NU-88 powder as a seed crystal.
By studying the IM-5 products prepared according to the documents above, it can be seen that the IM-5 molecular sieves prepared from prior arts have an morphology of two dimensional rodlike form with a diameter of generally 50 nm or more and an aspect ratio of generally about 5. Regarding a two dimensional rodlike molecular sieve, the aspect ratio determines the proportional relation between the crystal face in the radial direction and the crystal face in the axial direction. The more the aspect ratio is, the more the area of the periphery crystal face, and correspondingly the less the area of the sectional plane crystal face. It is currently known that a certain crystal face of a crystalline material has specific reactivity, such that the more the crystal face exposes, the higher the corresponding reaction selectivity. Therefore, by controlling the proportional relation between the periphery crystal face and the sectional crystal face through the aspect ratio of the two dimensional rodlike molecular sieve, the reaction selectivity of the corresponding crystal face can be increased.